[verg]

Just got back from my first Finite Mathematics discussion. My TA, who is one of the worst "engrish" speakers I have ever heard, hands out a sheet with some problems that are suppose to give us an idea of things we will be learning during the semester. The first problem reads as follows:

<font color="blue"> Somebody throws balls at a target. There is a 50 percent chance that she hits with each ball. What is the chance that she hits the target at least once when she throws 3 balls? </font>

The TA gives us a little time to work out the problem then goes into his solution. Which follows:

<font color="red"> 50% + 50% + 50% = 150% she hits the target at least once </font>

No one in the classroom says anything for a few seconds and finally I ask how we can have a probability greater than 100%. He runs over the problem again using the same method. I'm still confused and say so. He explains his thinking, which makes no sense because of his "engrish". So I just pretend like I understand and shut up the rest of the class.

How can someone not understand basic probability and be TAing at a major university?

FWIW I go to the University of Wisconsin, which is a pretty reputable (although large) university.